The objective of this project is to provide a means for noninvasive assessment of the dynamics of blood flow within the coronary artery tree, coronary bypass grafts, and intracardiac channels. To achieve this objective, we propose to extend the capabilities of Doppler ultrasound by further development of an existing Doppler imaging system combined with a rigorous laboratory and clinical validation protocol. The Infinite Gate Pulse Doppler (IGPD), developed at this Institute under NIH Grant R01-HL23868, is the basic instrument to be used in this project. The current IGPD is a third generation device that appears to be both technically capable and economically practical for application to noninvasive assessment of coronary and cardiac dynamics. We propose to extend the capabilities of this device to provide two dimensional images of flow throughout the cardiac cycle, and document its ability to detect and measure flow as well as other derivable physiological parameters. These objectives will be accomplished through the completion of the following specific aims: (1) Development of an ECG gated, two-dimensional pulse Doppler sector scanner that will allow on-line acquisition, storage, analysis, and redisplay of coronary and cardiac dynamics, (2) Laboratory validation of the capabilities of the IGPD through in vitro measurements of flow phantoms and in vivo measurements on animal models, correlated with electromagnetic flowmeter measurements during surgery and post-operative measurements using implanted CW Doppler flowmeter cuffs, (3) Clinical validation of the IGPD capabilities through a double blind correlation of pulse Doppler results with radiographic findings during cardiac catheterization.